Molybdenum disulfide concentrates of relatively high grade have long been recognized and employed as an intermediate for synthesizing a variety of molybdenum compounds, as well as metallic molybdenum itself, which are of a corresponding high purity. Such high grade molybdenum disulfide concentrates consist of particles containing contaminating constituents which consist essentially of minerals such as potassium minerals, silica, silicates and other gangue constituents present in the original ore body from which the molybdenite is derived. Chemical feed stock or other high grade molybdenite powders normally contain less than 1.5% contaminants.
Molybdenum disulfide powders of the requisite high purity have heretofore been produced in accordance with prior art practices by subjecting an impure particulated molybdenite concentrate to a plurality of grinding, flotation and extraction operations to effect a progressive reduction in the quantity of contaminating constituents therein. While processes of the foregoing type have been successful for producing powders of satisfactory purity, the purification technique requires relatively large capital investment in equipment, is relatively costly to operate, is inefficient in removing contaminating mineral constituents, such as potassium minerals, from the concentrate, and produces a powder product in less than optimum yields based on the feed material processed.
In order to overcome the relatively high costs associated with the foregoing physical purification technique, a variety of chemical purification processes have heretofore been used or proposed, such as described in U.S. Pat. Nos. 2,686,156; 3,101,252 and 3,661,508. Such chemical purification techniques as described in the aforementioned patents have been effective to produce high purity molybdenum disulfide powders but have not overcome the problems associated with physical purification techniques; namely, the relatively high costs, complexity and capital expenditure in the practice of the purification process. Moreover, such chemical purification techniques require the use of substantial quantities of high cost chemical reagents and further require the use of waste treatment facilities for treatment of the effluents in order that they can harmlessly be discharged to waste.
The present process provides for a physical purification of impure molybdenite concentrate feed materials which overcomes many of the disadvantages and objections associated with prior art techniques, providing for improved efficiency in the removal of insoluble contaminating constituents, including potassium minerals; while at the same time, minimizing losses of the molybdenite constituent, providing a high purity product in comparatively high yields.